Document Type and Number:
Japanese Patent JPS5418641
Kind Code:
B2
Abstract:
A frame arranged to traverse a mast on a rotary drill apparatus for exerting an axial feed or pulldown force on a drill pipe and bit assembly and characterized by a pair of rotatable shafts each having two spaced apart pinions mounted thereon which are engaged with parallel gear racks mounted on the mast. The pinion shafts each have a sprocket mounted thereon driven by an endless chain connected to pulldown drive means mounted on the main deck of the apparatus. The pulldown chains are equally tensioned by a pair of hydraulic chain tensioning devices so that equal torque is exerted on the pinion shafts. The pinion shafts are spring mounted on the pulldown frame to compensate for misalignment of the gear racks with respect to each other.
Application Number:
JP2671574A
Publication Date:
July 09, 1979
Filing Date:
March 07, 1974
Export Citation:
International Classes:
E21B3/02; E21B7/02; E21B15/04; E21B19/08; E21B19/084